Art of distilling oils



Y latter.

re-introduce the stocks thus formed, name- Patented Nov. 1, 1927.

UNITED STA Rassuo TES PATENT OFFICE.

ROBERT E. HUMPHRE YS, OF 'WHITING, INDIANA, ASSIGNOR T0 STANDARD OIL COM- PANY, OF WHITING, INDIANA, A CORPORATION OF INDIANA.

ART DISTILLING OILS.

No Drawing.

The present invention relates to improvements in, the art of producing gasoline or hydrocarbon oils of the gasoline range of boiling points from hydrocarbon oilshaving higher boiling points. .It will be fully understood from the following description, in which specific methods for carrying the invention into effect are described.

The present invention relates particularly to methods for the production of hydrocarbon oils of the gasoline range of boiling points in. which gas oil or other distillate oil havingan initial boiling point of 600 F. or higher is initiallydistilled under a pressure of 60 to 100 lbs. per square inch. In the course of such distillation, hydrocarbon oils of the boiling point range of gasoline, say,-

from 120 F. to 394 F. are formed and distilled oif, usually accompanied by oils of a higher boiling point range, approximately that of the kerosene type of hydrocarbon oils. At the termination of such a distillation a tar or bottom is present in the still which contains small proportions of hydrocarbon oils of the boiling point range of kerosene and larger proportions of oil having the boiling point range of gas oil, that is, between 650 and 800 F. In the further handling of these products, the distillate from the pressure stills is redistilled to separate the gasoline, a residue of kerosene-like characteristics being obtained and the tar is separated into its various fractions, either by steam or dry distillation, ordinarily the It has hitherto been customary to i I 1y, the bottoms from the pressure-distillate and the fractions of the pressure tarhaving boiling-points not higher than those of gas.

oil into the stocks fed into the pressure stills in which the original distillation takes place, such stocks being designated as cycle stocks when so re-introduced.

In accordance with the present invention,

cycle stocks, that is, stocks recovered from' pressure-distilled materials and having boiling-points above the gasoline boiling point range, are introduced into a still operating at a pressure exceeding 300 "lbs. per square inch, and are therein distilled for the formation of gasoline. A commercially effective production of gasoline is procured therefrom and at the same time the average rate of production of gasoline from the stills operating at 4 to 6 atmospheres pressure is ma- App'lication filed March 31, 1922. Serial No. 548,531.

terially increased by reason of the elimination therefrom of the cycle stocks.

The present invention is illustrated by the following example:

A cut from crude oil having a boilingpoint range of, say 650 to 800 F., is charged into a still, which is gradually brought to the distillation point at a pressure of from 4 to 6 atmospheres, say 90 lbs. per square inch. A distillate is produced containing, for example, about of hydrocarbon oil boiling below 392 F., that is, of the gasoline range of boiling-points, the entire distillate having a maximum boiling point of about 600 F. The pressure distillation is continued, oil of the character of the original oil charged into thestill being fed thereinto at a rate such as to maintain substantially a constant volume of oil in the still. The distillation is continued until the residue or bottom in the still has a volumeof about 45% of the volume of the original charge. Upon termination of the distillation the pressure distillate is redistilled, preferably with steam, and the fraction having the gasoline range of boiling points is removed therefrom, a pressure distillate bottom or residue having a boiling point range of 350 to 600 F. -remaining. This residue or bottom, having a gravity of 35.5 to 36.5 Baum, is charged into a still and heated under a pressure in excess of 300i, lbs. per square inch, say 325 lbs. In this distillation the liquid still contentsmay attain a temperature of 740 to 765 F The vapors evolved, which contain alarge proportion of gasoline constituents, are condensed,'either under the pressure of distillation or a lower pressure. This distillate may be redistilled to separate the gasoline constituents, and the bottom from this last distillation added to the cycle stocks introduced into the high pressure still. Other cycle stocks, for example, those derived from the tars or residues obtained in the low pressure still, may be treated in the high pressure still in like manner.

I claim:

1. The improved method of manufacturing gasoline which consists in distilling a hydrocarbon oil distillate having a boiling point range of 650 to 850 F. under a pressure of 60 to lbs per square inch, separating from the products of such distillation a distillate stock having an initial boiling point approximating the maximum boiling point of gasoline, and redistilling the separated stock under a pressure in excess of 300 lbs. per square inch .for the further formation of gasoline.

2. The improved method of manufacturing gasoline which consists in distilling under pressure a hydrocarbon oil distillate having an initial boiling point above the gasoline boiling point range, thereby producing a distillate containing gasoline and 1 heavier fractions,' separating the heavier fractions from the gasoline in said distillate and subjecting the heavier fractions of said distillate from the pressure distillation to a further distillation under a pressure in excess of 300 lbs. per square inch.

ROBERT E. HUMPHREYS. 

